Hi all, I drive a 1999 Chevy Tahoe which I believe has an electrical problem. A faint but distinct high-pitched whistle is audible whenever the engine's rpms are high, almost like a turbo-charger. Additionally, the interior dash lights flicker slightly at the same time. I have an iPod radio transmitter which picks up this whistle and amplifies it (much to my dismay) when I listen to music, so I'm sure the problem is somewhere in the electrical system.
What are the possible causes? I have replaced the alternator, so that shouldn't be it. This is driving me crazy!